/****************************************************************
*	Navigation Functions for
*	web.ist.utl.pt/~ist162457/   by MMelo
*****************************************************************/

function currentYPosition() {
	if (self.pageYOffset)
		 return self.pageYOffset;
	if (document.documentElement && document.documentElement.scrollTop)
		return document.documentElement.scrollTop;
	if (document.body.scrollTop)
		 return document.body.scrollTop;
	return 0;
}
function elmYPosition(eID) {
	var elm  = document.getElementById(eID);
	var y    = elm.offsetTop - 55;
	var node = elm;
	while (node.offsetParent && node.offsetParent != document.body) {
		node = node.offsetParent;
		y   += node.offsetTop;
	} return y;
}
function smoothScroll(eID) {
	var startY   = currentYPosition();
	var stopY    = elmYPosition(eID);
	var distance = stopY > startY ? stopY - startY : startY - stopY;
	if (distance < 100) {
		scrollTo(0, stopY); return;
	}
	var speed = Math.round(distance / 100);
	if (speed >= 20) speed = 20;
	var step  = Math.round(distance / 25);
	var leapY = stopY > startY ? startY + step : startY - step;
	var timer = 0;
	if (stopY > startY) {
		for ( var i=startY; i<stopY; i+=step ) {
			setTimeout("window.scrollTo(0, "+leapY+")", timer * speed);
			leapY += step; if (leapY > stopY) leapY = stopY; timer++;
		} return;
	}
	for ( var i=startY; i>stopY; i-=step ) {
		setTimeout("window.scrollTo(0, "+leapY+")", timer * speed);
		leapY -= step; if (leapY < stopY) leapY = stopY; timer++;
	}
}
